Vitiligo is a condition that causes depigmentation of skin, typically in sections or patches, and affects about 1-2% of the world population. Vitiligo occurs when there is an absence of functional melanocytes (melanin-producing cells) in the skin. Vitiligo also can affect the mucous membranes and the eye. There may be a genetic predisposition to vitiligo in some cases. The average age at vitiligo onset is about 20 years, with onset most commonly observed between the ages of 10 and 30.
Vitiligo occurs most often on the face and extremities—typically the hands and wrists. Depigmentation also can occur around the mouth, eyes, nostrils, genitalia, and umbilicus. Depigmented patches are flat areas of normal-feeling skin, and may have a hyperpigmented edge. The edges typically are well-defined but irregular. In trichrome vitiligo, there is an intermediate zone of hypochromia between the achromic center and peripheral unaffected skin.
There are several clinical classifications of vitiligo. Segmental vitiligo presents as one or more macules in a dermatomal or quasidermatomal pattern, and occurs most commonly in children. All other types of vitiligo are classified as non-segmental vitiligo, which is most common. Focal vitiligo is characterized by depigmentation in one area, or macule, such as the trigeminal nerve distribution. Other forms of non-segmental vitiligo often produce symmetric patches, sometimes covering large areas. Mucosal vitiligo affects only mucosal membranes. Generalized vitiligo may be acrofacial, in which depigmentation occurs on the distal fingers and periorificial areas, or vulgaris, which is characterized by widely distributed, scattered patches. Universal vitiligo manifests as complete or nearly complete depigmentation, and frequently is associated with multiple endocrinopathy syndrome. The exact cause of melanocyte loss in vitiligo remains debatable, but recent observations have pointed to a role for cellular immunity in the pathogenesis of vitiligo (see, for example, Wang et al. (2011) Th17 Cells and Activated Dendritic Cells Are Increased in Vitiligo Lesions. PLoS ONE 6(4): e18907). Despite some advances in elucidating the origins of the disorder, current therapies, such as topical corticosteroids, topical immunomodulators and psoralen phototherapy have serious side effects and limited therapeutic utility. Vitiligo is a disfiguring disease for which current therapies have proven unsatisfactory.